Nurhavati, NurhavatiMuhdarina, MuhdarinaLinggawati, AmiliaAmri, Tengku Ariful2018-10-222018-10-222018-10-222461-0968wahyu sari yenihttp://repository.unri.ac.id/handle/123456789/9459Biodiesel is one of an environmentally friendly alternative fuels. This study aimed to synthesize biodiesel from waste frying oil by the two step catalytic process, esterification of free fatty acids using sulfuric acid catalyst and transesterification of trigycerides using Cao catalyst derived from blood cockle shells (anadaro granosa). Cao catalyst was prepared by coarsely grounded cockie shell using a mortar pestle, dried in an oven at 110 °C for overnight and calcined at 900 °C for 10 hours. The optimum conditions of the esterification and transesterification processes was evaluated by varying temperature and time of reaction for both processes. The biodiesel conversion was analyzed by using GC and the biodiesel chacteristics were analized and the results were compared to Standar National for Biodiesel (SNI 04-7183-2006). The maximum yield of biodiesel was 80.04% at reaction conditions of H2504 catalyst was 3%, the mole ratio of oil: methanol was 1:18, temperature was 70°C, and reaction time was 2 hours, and the transesterification condition were temperature at 60°C, and reaction time for 3 hours. The characteristics of biodiesel were in the range of standar for biodiesel (SNI 04-7183-2006).enBiodieselwaste frying oilesterificationtransesterificationCaO heterogeneous catalystArticle